1. Field of the Invention
This invention relates to the field of dual stage actuator (DSA) type suspensions for disk drives including hard disk drives. More particularly, this invention relates to the field of a dual stage actuator suspension in which the microactuators are connected to the gimbaled region through flexible connectors.
2. Description of Related Art
Magnetic hard disk drives and other types of spinning media drives such as optical disk drives are well known. FIG. 1 is an oblique view of an exemplary prior art hard disk drive and suspension for which the present invention is applicable. The prior art disk drive unit 100 includes a spinning magnetic disk 101 containing a pattern of magnetic ones and zeroes on it that constitutes the data stored on the disk drive. The magnetic disk is driven by a drive motor (not shown). Disk drive unit 100 further includes a disk drive suspension 105 to which a magnetic head slider (not shown) is mounted proximate a distal end of load beam 107. The “proximal” end of a suspension or load beam is the end that is supported, i.e., the end nearest to base plate 12 which is swaged or otherwise mounted to an actuator arm. The “distal” end of a suspension or load beam is the end that is opposite the proximal end, i.e., the “distal” end is the cantilevered end. “Proximal” as a relative term means closer to the actuator arm to which the suspension is affixed, and “distal” as a relative term means closer to the cantilevered end of the suspension.
Suspension 105 is coupled to an actuator arm 103, which in turn is coupled to a voice coil motor 112 that moves the suspension 105 in an arc in order to position the head slider over the correct data track on data disk 101. The head slider is carried on a gimbal which allows the slider to pitch and roll so that it follows the proper data track on the disk, allowing for such variations as vibrations of the disk, inertial events such as bumping, and irregularities in the disk's surface.
Both single stage actuated disk drive suspensions and dual stage actuated (DSA) suspension are known. In a single stage actuated suspension, only voice coil motor 112 moves suspension 105.
In a DSA suspension, as for example in U.S. Pat. No. 7,459,835 issued to Mei et al. as well as many others, in addition to voice coil motor 112 which moves the entire suspension, at least one microactuator is located on the suspension in order to effect fine movements of the magnetic head slider and to keep it properly aligned over the desired data track on the spinning disk. The microactuator(s) provide much finer control and increased bandwidth of the servo control loop than does the voice coil motor alone, which only effects relatively coarse movements of the suspension and hence the magnetic head slider. Various locations have been proposed for the microactuator(s). The PZTs can be located within baseplate 105, on the load beam 107, or at or near the head gimbal assembly which is located at the distal end of load beam 107. Mei FIGS. 1 and 10 show embodiments in which the microactuators extend from the mount plate, and in which the microactuators are mounted in the middle of the load beam, respectively. Patent publication no. US2001/0096438 by Takada et al. and US2009/0244786 by Hatch show DSA suspensions in which the microactuator are located on the gimbal. U.S. Pat. No. 6,760,196 to Niu et al. shows a collocated microactuator, i.e., a microactuator that lies directly underneath the head slider. U.S. Pat. No. 6,376,964 to Young at al. shows microactuators that bend from side to side and that extend from the distal end of the suspension to the gimbal to effect fine movements of the slider through a hinged linkage structure.
FIG. 2 is a top plan view of the prior art DSA suspension 105 of FIG. 1. Microactuators 14, which are usually but not necessarily piezoelectric (PZT) devices, are mounted on microactuator mounting shelves 16 that are formed in mount plate 12. Microactuators 14 span gap 18.
DSA suspensions having the microactuators on the mount plate such as in FIG. 2 generally have high stroke length per unit of input voltage. This will be referred to simply as having high stroke length for shorthand. Such suspensions, however, usually suffer from low servo bandwidth due to resonances in the part of the suspension that is distal to the PZTs. DSA suspensions in which the microactuators are mounted on the gimbal, or act directly on the gimbal, are sometimes referred to as gimbal-mounted dual stage actuated suspensions, or “GSA” suspensions. Slider based (collocated) DSA suspension designs variously have the disadvantages of: requiring additional piece parts; requiring complicated tracing routing, electrical connections, and slider bonding; having heavy slider/tongue assemblies which is undesirable because the extra mass can affect dynamic performance especially under shock conditions; and requiring one or more dedicated tongue features that are prone to manufacturing tolerance issues. Other gimbal-based designs require thin-film PZTs for high stroke lengths, and/or can be difficult to adjust for pitch and roll static attitude.
In the discussion which follows, the microactuator(s) will be referred to as two PZTs for shorthand, although it will be understood that the invention applies equally to suspensions having only a single microactuator and/or microactuator(s) that are not necessarily PZT devices.
As used herein, the term “proximal” means closest to the actuator arm at which the suspension is mounted, i.e., toward the bottom of FIG. 2, and “distal” means closest to the cantilevered end of the suspension, i.e., toward the top of FIG. 2.